Photo-induced 2,4-D abatement on goethite surfaces in water containing H2O2, fluoride, and bicarbonate at neutral pH

JULIAN RENGIFO; GUILLERMO MUÑOZ MEDINA; JOH JAIRON ALVEAR DAZA; FRANCISCO SANCHEZ; HECTOR MARIO GUTIERREZ ZAPATA; ANDREA VILLASANTE APARICIO; JANETH SANABRIA

Natal

Congreso; IV Iberoamerican conference on advanced oxidation technologies; 2019

Universidad Federal de Rio Grande del Norte

Goethite was synthesized and characterized by severalanalytical techniques such as Mossbauer spectroscopy, X-ray photoelectronspectroscopy, diffuse reflectance spectroscopy and X-ray diffraction. Thenphotocatalytic activity at initial concentrations of 0.3 mg L-1 wasevaluated in the removal of 2,4-D (30 mg L-1) at pH 6.9 in presence(10 mg L-1) or absence of H2O2 upon simulatedsolar light (300 W m-2). Results revealed that 2,4-D was onlyremoved under the simultaneous presence of goethite, H2O2and simulated sunlight. In presence of high amounts of fluoride andbicarbonate, 2,4-D removal was strongly enhanced. Fluoride can modify thesurface of iron (hydr)oxide leading to the formation of Fe-F bonds benefitingthe formation of free ?OH radicals and producing band bendingshifting the conduction band flat potential towards negative values anddecreasing the electron-hole recombination. Bicarbonate reacts with ?OHradicals generating CO3-? species able to participate in2,4-D oxidation as well.